All of the subjects will be participants in an ongoing double-blind placebo-controlled trial (05-M-0225) of a glutamate antagonist, the drug riluzole, for Obsessive-Compulsive Disorder (OCD). The subjects are male and female children and adolescents, ages 7-17 years. They will all have met criteria for clinically significant OCD and will have failed to benefit from standard-of-care treatments or have been unable to tolerate the treatments. Some of the subjects will also have a diagnosis on the autism spectrum.